Diamonds an Edwardian youth saw (5)
I believe the answer is:
dated
'saw' is the definition.
(to date someone is to see them romantically)
'diamonds an edwardian youth' is the wordplay.
'diamonds' becomes 'd' (abbreviation for the card suit diamonds).
'an edwardian youth' becomes 'ated' (I can't justify this - if you can you should believe this answer much more).
'd'+'ated'='DATED'
Can you help me to learn more?
(Other definitions for dated that I've seen before include "not without romantic engagements" , "Outmoded" , "out of the ark" , "Old-fashioned" , "Met socially by arrangement" .)